Identification of monozygotic twin chimpanzees by microsatellite analysis

Zygosity determination is important for epidemiological, biological, obstet ric, and prognostic studies in both human and nonhuman primates. In this st udy, microsatellite loci were used to screen a pair of chimpanzee (Pan trog lodytes) twins and their parents. The twins share identical alleles at all loci tested. The probability of dizygotic origin is estimated to be 2.9 x 1 0(-11). Even after excluding linkage of loci on the same chromosome, the pr obability is still low enough (3.7 x 10(-9)) to exclude dizygotic origin. M HC typing was also done on Patr-DRB and Patr-DQB loci and the twins share i dentical alleles at both loci, consistent with the microsatellite results. Together these results demonstrate a monozygotic origin for the chimp twins . Our results suggest that microsatellite analysis is a powerful method for zygosity determination, which can be screened reliably and efficiently. Am . J. Primatol. 52:101-106, 2000. (C) 2000 Wiley-Liss, Inc.